Electrolytic apparatus



Dec. 10, 1963 1:..1. EVANS 3,113,918

ELECTROLYTIC APPARATUS Filed Nov. 8. 1960 3 Sheets-Sheet 1 WVE/YTOE 0Awd Evans wwhm ArmeA/Exr Dec. 10, 1963 D. J. EVANS 3,113,918

ELECTROLYTIC APPARATUS Filed Nov. 8. 1960 3 Sheets-Sheet 2 @W Mhmm Dec.10, 1963 D. J. EVANS 3,113,918

ELECTROLYTIC APPARATUS Fiied Nov. 8. 1960 s Shgets-Sheet s M/viwozDav/Id Eva/1s (EMA/NM 3,113,918 ELECTRQLYTTQ APPARATUS David JohnsonEvans, 215422 High Holhorn, London, England Filed Nov. 8, 1.969, ger.No. 68,019 9 Claims. (Cl. 264-268) This invention relates toelectrolytic apparatus including relatively small-scale apparatus forproduction of chlorine or hypochlorite for sterilising purposes andlargescale apparatus such as electrolysers for production of chlorine orhypochlorite directly in large volumes of sea-Water, for examplecondenser cooling water.

The electrodes usually employed in such apparatus are made of graphitewhich is liable to erosion in normal use, eventually resulting inirregular action and even destruction of the electrodes.

It is known that platinum is far more resistant to chemical action thangraphite, and that titanium is very resistant to such action. By coatingthin sheets of titanium with platinum, it is therefore possible toproduce composite metallic electrodes of substantial thickness,sutiiciently rigid for practical purposes, without the high cost ofplatinum electrodes.

The present invention has for its main object to provide improvedelectrolytic apparatus employing electrodes consisting of th n sheets oftitanium coated with platinum, and having far higher efiiciency thanapparatus emplo ing graphite electrodes, which would have to be made ofmuch larger size to give equal output.

The invention thus has the further objects of enabling relatively smallapparatus to be employed and of facilitating provision for cooling byliquid circulation, which is readily applicable when required.

A specific object of the invention is to ensure rapid discharge of theelectrolyte and the electrolytic products by arranging the thin sheetsof titanium, coated with platinum on one face, to form a stack with theelectrodes inclined at an angle and suitably spaced apart, theirplatinum-coated faces being uppermost, and with the electrolyte and theelectrolytic products from the uppermost faces passing upwards todischarge.

Other objects and advantages of the invention will hereinafter appearfrom the'following description of two embodiments given with referenceto the accompanying drawings, in which:

FIG. 1 is an elevation, partly in section, of a first embodiment havingelectrodes of flat rectangular shape.

FIG. 2 is a half-section on the line 22 of FIG. 1.

FIG. 3 is a sectional elevation of a second embodiment having eelctrodesof dished shape.

FIG. 4 is a section at right angles to FIG. 3.

In the embodiment shown in FIGS. 1 and 2, the electrodes consist of fiatsheets 19 of rectangular shape, composed of titanium with a coating ofplatinum, these sheets being mounted between two former plates 11 havingparallel and vertical inner faces formed with grooves 12, inclined at anangle of about 45 degrees. The electrodes have their opposite edgesfitted into the grooves so as to form a sloping stack with gaps of about2 mm. between their faces, and preferably having edge-sealing by the useof suitable insulating material. Each of the two end electrodes has abacking disc 13 secured centrally thereto by countersunk-headed screws14, and is also secured by screws to a bevel-faced block 15 throughwhich there passes alead-in or conductor rod 16 fixed to the backingdisc 13.

The assembly of electrodes 19, former plates 11 and bevel-faced blocks15 is slidably fitted into a tubular housing 17, the areuate outer facesof the former plates 11 being curved to the same radius as the interiorof the housing, and the two blocks 15 with their conductor rods UnitedStates Patent 0 16 being maintained above the axis of the housing byledges or millings 18 on the inner faces of the former plates 11, thegrooves 12 in the latter stopping short at this same level. The tubularhousing 17, which may be made of polyvinyl chloride or like plastic, hastwo rings 19 surrounding its ends; these rings, which act like jointingflanges, may be either screwed on the exterior of the housing as at Ellor fixed thereto by other means. Between the ends rings 19, the housingis surrounded by a metallic casing 21 made in two semi-cylindricalhalves, which are held together by bolted joints at lugs or flanges 22formed at their longitudinal edges. Circular cover plates 23, alsopreferably made of plastic material, are secured to the end rings bybolts or the like, a metal clamping plate 24 being arranged on theoutside of each cover plate for engagement by the bolts or the like. Themetal clamping plate also facilitates the attachment of end connections,such as an inlet 25 for electrolyte at one end of the housing; leadingto the space below the electrodes 12, an outlet 26 at the other end ofthe housing, leading from the space above the electrodes 12, andjunction-boxes 27 inside which the conductor rods are connected to theexternal leads. Brackets 28 or the like may be welded or otherwisesecured to the casing 21 outside the housing, or to an outer jacketsurrounding the casing, if cooling is required. Internal cooling mayalso be provided by forming passages in the interior of the electrodes12, for example by Welding two platinised sheets together at their edgesto form an electrode, the coolant flowing through the internal passages.

In another embodiment of the invention, as shown in FIGS. 3 and 4, thetitanium electrodes consist of dished or frusto-conical discs 30 slippedupon a central tube 31 and separated from one another by spacing washers32 of insulating material. The central tube is arranged to besubstantially vertical, and the discs 3%, which are platinised on theupper face only, are mounted with their apertured centers above theirouter edges, advantage being taken of this position and of the shape ofthe cathodic surface for the discharge of hydrates when the polarity ofthe cell is temporarily reversed from time to time, the hydrates thendropping from the outer edges of the cathodic surfaces and falling fromthe peripheries of the underlying discs. The stack of discs 30 issupported by a sleeve 33 resting upon a base 34, and a second sleeve 35is fitted on top of the stack, both sleeves being made of a suitableplastic.

The whole assembly is enclosed in a housing 36 of suitable insulatingmaterial, to which a top cap 37 and the bottom cap or base 34 aresecured, for example by means of clamping plates 38 and bolts 38-.

The shape of the discs 39 lends itself to insulation of the edges bydipping in a suitable plastic. The uppermost electrode 30 may becompletely covered with this plastic insulating material on its anodicface, the lead-in conductor rod 39 attached to this electrode being alsocovered with the insulating material, and its extremity being carriedthrough the cap 37 at the top of the cell by way of a hole 49 which maybe provided with a suitable gland. The bottom electrode of the stack mayalso have its attached conductor rod 41 covered with insulated materialand it may extend through a gland in the bottom cap or base 34.

The central tube 31 is preferably arranged for circulation of coolants,being made of silica glass or other hear-resistant material; if coolingis not required, the tube may be of any suitable plastic material, andit may be perforated to serve as the outlet for the hydrogen andelectrolytic product, the top sleeve 35 being similarly perforated toregister with the tube perforations.

The tube 31 preferably leaves an annular space between it and the edgeof the central aperture in each electrode, to allow for the exit ofhydrogen and the circulation of the electrolyte, or it may be ribbedexternally to leave spaces inside the washers 32 separating theelectrodes from one another, so that the hydrogen and elec trolyte maypass out beneath the sleeve 35. The electrolyte then flows out through apipe 42, which preferably projects below the top cap 37, while thehydrogen collects above the inner end of this pipe and escapes through aseparate pipe 43, the inner end of which is flush with the top cap.

In some cases the bottom cap or base 34 may be hollowed out to provide aspace of conical shape to receive hydrates when thrown off theelectrodes, a suitable vent being positioned near the bottom to allowthese deposits to be blown down from time to time. Operation of thevalve controlling blow-down may be automatically sequenced with thereversal of polarity. Preferably, however, the inlet 44 for electrolyteprojects through the bottom cap or base 34 for a suflicient distance toensure that the hydrates are trapped without falling back into theinlet, and a drain pipe 45 for removal of the hydrates is provided, theinner end of this pipe being flush with the base 34.

It will be seen that this embodiment allows for variation of the numberof electrodes in a very simple way, the tube 36 being readilyreplaceable by one of a diiferent length, and that the cell may beassembled from standard parts to suit different requirements of voltageand output.

Automatic venting of hydrogen may be arranged for by the use of a normalliquid outlet in the top cap 37, with the central tube 31, on which theelectrodes 30 are mounted, extending upwards for a relatively greatlength; the bottom of this tube will be sealed below the base 34, itsupper portion and the sleeve 35 being perforated above the electrodes toallow entrance of the hydrogen, which can thus escape at the top end ofthe tube 31. This arrangement will be particularly suitable for treatingsea-water, which normally needs no cooling, but can be allowed to flowout through the central tube together with the hydrogen and theelectrolytic product.

The invention is not limited to the embodiments described by way ofexamples; thus the second embodiment described may be modified byreversing the relative position of the frusto-conical electrodes.

What I claim is:

1. Electrolytic apparatus comprising a container, said container havingopposite end portions, said container defining a closed cavitytherewithin, a liquid inlet at one end of said container incommunication with said cavity, a liquid outlet at the opposite end ofsaid container in communication with said cavity, said liquid outletbeing disposed a substantial distance vertically above said liquid inletwhen said container is in its operative position, a stack ofelectrically conductive bipolar electrodes disposed within said cavityand positioned vertically between said inlet and said outlet, saidelectrodes being insulated from one another and closely spaced from oneanother in substantially parallel relationship, all of said electrodesbeing inclined at a substantial angle to the vertical, each of saidelectrodes comprising a thin sheet of titanium coated with platinum ononly one face thereof, the platinum coated face of each electrode beingthe upwardly directed face of the inclined electrode, and means forimpressing an electrical potential between the electrodes at oppositeends of said stack of electrodes.

2. Apparatus as defined in claim 1, wherein said electrodes are flatsheets, supporting means within said container, said supporting meansdefining a plurality of parallel grooves, edge portions of the fiatsheet electrodes being mounted in said grooves.

3. Apparatus as defined in claim 2, wherein the supporting meanscomprises two former plates mounted parallel to one another, said formerplates each having a substantially vertical inner face having groovesformed therein and inclined at an angle of substantially 45 to thevertical.

4. Apparatus as defined in claim 3, wherein the former plates havearcuate outer surfaces, the container having a circular internalcross-sectional configuration, the assembly of electrodes and formerplates being slidably mounted within said container.

5. Apparatus as defined in claim 4, wherein said container includes twoend plates, the liquid inlet being disposed in one of said end platesand the liquid outlet being disposed in the other of said end plates,the means for impressing an electrical potential between the electrodesat opposite ends of the stack of electrodes comprising a pair of blocksof electrically insulating material having flat end faces disposed at anangle of substantially 45 to the vertical and defining aperturestherethrough, each of said blocks having an end face, the blocks beingso positioned within the container that the end faces of the blockscontact an adjacent electrode of the stack over substantially the wholearea of the respective end faces, the end electrodes at opposite ends ofthe stack of electrodes being mechanically attached to the adjacentblocks, and a rod of electrically conducting material attached to theend face of each of said blocks and passing through the aperture in theassociated block and extending to the exterior of said container.

6. Apparatus as defined in claim 1, wherein each of said electrodes isof dished substantially frusto-conical configuration and has a centralaperture formed therethrough, support means mounted within saidcontainer and comprising a tube engaging the edges of the centralapertures in the electrodes and extending therethrough, and spacingWashers disposed between adjacent electrodes.

7. Apparatus as defined in claim 6, wherein said tube is verticallymounted within the container, the container being provided with top andbottom caps, said tube being mounted between said caps, electricalcurrent lead means extending from the outside of the container to theuppermost and lowermost electrodes within the container, the liquidinlet being disposed in the bottom cap and the liquid outlet beingdisposed in the top cap.

8. Apparatus as defined in claim 7, wherein the substantiallyfrusto-conical electrodes are positioned with the apices of the conesuppermost, the mounting tube and the central apertures in saidelectrodes being arranged such that spaces are defined between the tubeand the edges of said apertures.

9. Apparatus as defined in claim 8, wherein the liquid inlet projectsabove the bottom cap and into the container at a point within theorthogonal projection of the electrodes onto the bottom cap, the bottomcap being provided with a drain outlet to the exterior whose inner endis flush with the inner surface of the bottom cap.

References Cited in the file of this patent UNITED STATES PATENTS728,440 Boucher May 19, 1903 1,062,058 Threlfall May 20, 1913 2,636,856Suggs Apr. 28, 1953 2,955,999 Tirrell Oct. 11, 1960 FOREIGN PATENTS514,171 Germany Dec. 10, 1930 1,220,408 France Jan. 4, 1960 132,953Australia May 31, 1949 604,415 Canada Aug. 30, 1960 13,723 Great Britain'of 1893

1. ELECTROLYTIC APPARATUS COMPRISING A CONTAINER, SAID CONTAINER HAVINGOPPOSITE END PORTIONS, SAID CONTAINER DEFINING A CLOSED CAVITYTHEREWITHIN, A LIQUID INLET AT ONE END OF SAID CONTAINER INCOMMUNICATION WITH SAID CAVITY, A LIQUID OUTLET AT THE OPPOSITE END OFSAID CONTAINER IN COMMUNICATION WITH SAID CAVITY, SAID LIQUID OUTLETBEING DISPOSED A SUBSTANTIAL DISTANCE VERTICALLY ABOVE SAID LIQUID INLETWHEN SAID CONTAINER IS IN ITS OPERATIVE POSITION, A STACK OFELECTRICALLY CONDUCTIVE BIPOLAR ELECTRODES DISPOSED WITHIN SAID CAVITYAND POSITIONED VERTICALLY BETWEEN SAID INLET AND SAID OUTLET, SAIDELECTRODES BEING INSULATED FROM ONE ANOTHER AND CLOSELY SPACED FROM ONEANOTHER IN SUBSTANTIALLY PARALLEL RELATIONSHIP, ALL OF SAID